This contribution outlines the historic development of Clinical Ecology (CE) and the differences it poses to scientific environmental medicine. The pathogenic, diagnostic and therapeutic concepts of clinical ecology are presented and critically acknowledged. Particular attention is given to behavioral and mental illnesses which, according to the beliefs of clinical ecologists, are related to food and chemicals, whereby this occurrence is considered a "cerebral allergy". The term "allergy" is, however, understood in the broader sense, as opposed to the usual medical term, to include non-immunological, pseudo-allergic and other intolerance reactions. Below are details of the validity and effectiveness of clinical ecology methods. Clinical ecology is concerned, not least, with unspecified, little understood health disorders and chronically fluctuating illnesses which are mainly attributed by clinical medicine to psychosomatic complaints. Many patients are critical of the lack of an adequate, literally "integral" treatment, i.e. one which also includes psychosocial aspects. They tend to search for simple answers and "alternative" treatment possibilities associated with it. Clinical ecologists and other "alternative practitioners" respond to this demand. They initially confirm or suggest to the patient the possibility of poisoning and offer a therapy that is allegedly causal and effective. The iatrogene fixation of patients with environment related illnesses has become a problem for the person in question, clinical medicine and the insured. Of course, those affected interpret their situation in another way. They consider themselves to be the victims of medical ignorance. The challenge posed by unconventional schools of medical thought should be met by increased efforts to create "sound medical practice" and by the attempt to achieve generally binding criteria for quality in the sense of effective "consumer protection".